1. Field of the Invention
The present invention relates to a magenta toner for use in electrophotography, electrostatic recording, electrostatic printing, or toner jet recording, the magenta toner containing a compound having an azo skeleton as a dispersant.
2. Description of the Related Arts
Magenta pigments typically used as colorants for magenta toners are difficult to disperse due to small pigment particle size. If the pigment is not sufficiently dispersed in the toner particles, the coloring power of the toner particles is degraded. This has also led to other problems such as significant fluctuation in charging properties due to environmental changes such as changes in temperature and humidity and a high incidence of “fogging”, that is, development of the toner on background portions of images.
Japanese Patent Laid-Open No. 2006-30760 discloses a technique for dispersing a pigment in a toner. According to this technique, a particular polymer dispersant is used in combination with a magenta pigment to enhance the dispersibility of the magenta pigment and improve the coloring property and charging property of the toner. Japanese Patent Laid-Open No. 11-231572 discloses a method for satisfactorily dispersing a coloring material in a toner by use of a pigment derivative and a polymer dispersant. Japanese Patent Laid-Open No. 2003-202697 discloses a pigment dispersant in which a quinacridone is covalently bonded to a polymer.
Japanese Patent Laid-Open No. 2-210459 proposes a method that uses a diketopyrrolopyrrole-based pigment instead of a quinacridone pigment in order to improve the charging stability of the magenta toner and suppress fogging.